Displacement flow diffusers discharge the air from air conditioning systems with a low velocity and near the floor. The low-turbulence airflow creates a pool of fresh air that covers the entire floor area. The convection from people and other heat sources causes the fresh air from the pool to rise and create comfortable conditions in the occupied zone.

This draught-free and economical type of ventilation is also suitable for large internal spaces, with several regularly arranged units.

Displacement ventilation is characterised by low airflow velocities and low turbulence. The air quality in the occupied zone is very high.

Displacement ventilation with air discharge near the floor is suitable only for cooling. The maximum supply air to room air temperature difference is –6 K.

Type QLE displacement flow diffusers are fitted with a perforated sheet metal basket as an equalising element; it distributes the supply air flow equally across the entire diffuser area. The perforated sheet metal diffuser face helps to equalise the airflow further. One-way air discharge.

With displacement ventilation, i.e. air discharge near the floor, extract air units should be installed in the upper part of a room, above the occupied zone.

Nominal sizes (B × H)

1000 × 150 to 1500 × 750 mm

Minimum volume flow rate, at 0.1 m/s

15 – 115 l/s or 54 – 414 m³/h

Maximum volume flow rate, at 0.3 m/s

45 – 340 l/s or 162 – 1224 m³/h

Supply air to room air temperature difference

–6 to –1 K

Sound power level, at 0.3 m/s

42 dB(A) max.

Quick sizing tables provide a good overview of the volume flow rates and corresponding sound power levels and differential pressures.

QLE, sound power level, total differential pressure and near zone

Nominal size

V

v0

Δpt

LWA

Lnz

Nominal size

l/s

m³/h

m/s

Pa

dB(A)

m

1000 × 150

15

54

0.10

<3

<15

<

1000 × 150

25

90

0.17

<3

<15

<

1000 × 150

30

108

0.20

<3

<15

<

1000 × 150

45

162

0.30

3

20

<

1250 × 150

20

72

0.11

<3

<15

<

1250 × 150

30

108

0.16

<3

<15

<

1250 × 150

40

144

0.21

<3

16

<

1250 × 150

55

198

0.29

4

26

<

1500 × 150

25

90

0.11

<3

<15

<

1500 × 150

40

144

0.18

<3

16

<

1500 × 150

55

198

0.24

4

26

<

1500 × 150

70

252

0.31

7

33

<

1000 × 300

30

108

0.10

<3

<15

<

1000 × 300

45

162

0.15

<3

<15

<

1000 × 300

70

252

0.23

5

19

<

1000 × 300

90

324

0.30

9

27

<

1250 × 300

40

144

0.11

<3

<15

<

1250 × 300

65

234

0.17

5

17

<

1250 × 300

90

324

0.24

9

27

<

1250 × 300

115

414

0.31

14

35

<

1500 × 300

45

162

0.10

<3

<15

<

1500 × 300

75

270

0.17

6

21

<

1500 × 300

105

378

0.23

12

32

<

1500 × 300

135

486

0.30

20

40

<

1000 × 450

45

162

0.10

<3

<15

<

1000 × 450

75

270

0.17

3

<15

<

1000 × 450

105

378

0.23

5

21

<

1000 × 450

135

486

0.30

9

29

<

1250 × 450

55

198

0.10

<3

<15

<

1250 × 450

95

342

0.17

4

17

<

1250 × 450

135

486

0.24

9

29

<

1250 × 450

170

612

0.30

14

36

<

1500 × 450

70

252

0.10

<3

<15

<

1500 × 450

115

414

0.17

7

23

<

1500 × 450

160

576

0.24

13

34

<

1500 × 450

205

738

0.30

21

42

<

1000 × 600

60

216

0.10

<3

<15

<

1000 × 600

100

360

0.17

<3

<15

<

1000 × 600

140

504

0.23

4

20

<

1000 × 600

180

648

0.30

7

28

<

1250 × 600

75

270

0.10

<3

<15

<

1250 × 600

125

450

0.17

3

17

<

1250 × 600

175

630

0.23

7

27

<

1250 × 600

225

810

0.30

11

35

<

1500 × 600

90

324

0.10

<3

<15

<

1500 × 600

150

540

0.17

5

22

<

1500 × 600

210

756

0.23

10

33

1.37

1500 × 600

270

972

0.30

16

41

1.84

1000 × 750

75

270

0.10

<3

<15

<

1000 × 750

125

450

0.17

3

<15

1.25

1000 × 750

175

630

0.23

5

21

1.88

1000 × 750

225

810

0.30

9

29

2.57

1250 × 750

95

342

0.10

<3

<15

0.65

1250 × 750

155

558

0.17

4

17

1.15

1250 × 750

220

792

0.23

8

28

1.71

1250 × 750

280

1008

0.30

14

35

2.26

1500 × 750

115

414

0.10

<3

<15

0.64

1500 × 750

190

684

0.17

6

23

1.09

1500 × 750

265

954

0.24

12

33

1.56

1500 × 750

340

1224

0.30

20

41

2.04

<: 0.2 m/s are not achieved

The near zone values are based on a supply air to room air temperature difference of –3 K

Displacement flow diffusers for air discharge near the floor, suitable for comfort zones with special demands on architecture and design.

With one-way air discharge for low-turbulence displacement ventilation. Rectangular casing for installation on a wall.

Ready-to-install component which consists of a casing with spigot at the top or bottom, a perforated sheet metal basket as an equalising element, and a perforated sheet metal diffuser face.

Spigot suitable for rectangular ducts.

Sound power level of the air-regenerated noise measured according to EN ISO 5135.

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